1. Field of the Invention
The present invention relates to an exhaust adapter of a combustion apparatus having a burner, the exhaust adapter being used for connecting an exhaust pipe leading exhaust gas (combustion gas) to a desirable place to be discharged with an exhaust port of the combustion apparatus, and also relates to a combustion apparatus provided with the exhaust adapter.
2. Description of the Related Art
For example, a combustion apparatus of inside installation type generally adopts a means for leading combustion gas outside utilizing an exhaust pipe as a discharge means of combustion gas. In this case, an exhaust port for combustion gas is provided on an upper part of the combustion apparatus and the exhaust pipe is attached so as to rise upward from the exhaust port (for example, refer to Japanese examined Utility Model publication No. JP-55-80645-U1). One example of an attachment means of an exhaust pipe is that an exhaust adapter is attached to a member having an exhaust port and the exhaust pipe is fitted and coupled at the upper part of the exhaust adapter (for example, refer to Japanese unexamined Patent publication No. JP-2000-291939-A).
However, the above-mentioned conventional arts have the following problems to be solved.
In order to connect an exhaust pipe to an exhaust port of a combustion apparatus, one of two types of exhaust pipes with different pipe diameters is sometimes selected and used. Specific examples are as follows. Namely, the component cost is reduced when the diameter of the exhaust pipe becomes smaller. Therefore, it is desirable that an exhaust pipe with smaller diameter of two types of exhaust pipes with different pipe diameters is used as a standard one for general use. However, when the total length of the exhaust pipe considerably increases, the exhaust resistance becomes large, so that an exhaust pipe with large diameter is desirable in view of reducing the exhaust resistance as much as possible. Sometimes two types of exhaust pipes with different pipe diameters are selectively used based on different circumstances when the exhaust pipe is used.
In contrast, a conventional exhaust adapter has been designed to be connected with only one type of exhaust pipe. In such a case, two types of exhaust adapters are required to be prepared and to be used depending on the diameter of the exhaust pipe in order to selectively use two types of exhaust pipes with different pipe diameters. Such a selective use of the exhaust adapters is bothersome and inconvenient. Furthermore, preparation of two types of exhaust adapters costs much. Therefore, it is desired to solve such defects.
On the other hand, when combustion gas decreases in temperature while passing through the exhaust pipe and water vapor contained in the combustion gas condenses, highly acidic drain (condensate water) may be generated. When such drain flows outside of the exhaust adapter, there causes a problem that the outer surface of the combustion apparatus is contaminated by the drain. Therefore, it is desired not to have such a defect that the outer surface of the combustion apparatus is contaminated by the drain when the exhaust adapter is designed to be preferably used for two types of exhaust pipes with different pipe diameters.